The filing, in U.S. Bankruptcy Court in Bay City, Mich., puts an immediate halt to thousands of implant lawsuits against Dow Corning, including 200 set for trial in the next six months.

Dow Corning, a joint venture of Dow Chemical Co. and Corning Inc., said it filed for Chapter 11 protection because of the "exorbitant demands" from plaintiffs' attorneys in lawsuits involving silicone-gel breast implants.

Latest news videos

Dow Corning has agreed to pay $2 billion into a $4.2 billion settlement of 400,000 claims lodged by women over alleged health problems caused by the implants. Although U.S. District Judge Samuel Pointer, who is overseeing the settlement, has said the fund is too small, Dow Corning has said it will not pay more than the $2 billion it has committed over 30 years.

About 11,000 women have chosen to file separate lawsuits against the manufacturer. By declaring bankruptcy, Dow Corning has prevented the plaintiffs from proceeding with their cases. They must now submit their claims to bankruptcy court, where they will join other creditors.

If the claims are allowed, Dow Corning could be forced to pay billions more. By declaring bankruptcy, it has bought time.

More than 2 million American woman have received breast implants, about 80 percent of them for cosmetic reasons.

The implants can rupture, and some women have blamed the silicone for triggering immune system disorders, including scleroderma - a hardening of the skin resulting from abnormal fibrous tissue growth - and arthritis.

Dow Corning stopped making implants in 1990.

In early 1992, while Dow Corning was insisting its implants were safe, the Examiner reported that researchers had warned company officials as early as 1971 that the implants could pose a health hazard.

The U.S. Food and Drug Administration has banned their use for patients who want them strictly for cosmetic reasons.

Dow Corning joins other manufacturers that have sought the refuge of Chapter 11 against thousands of lawsuits over allegedly hazardous products, including Manville Corp., an asbestos maker, and A.H. Robins Inc., driven into bankruptcy over its Dalkon Shield intrauterine birth-control device.

Unlike asbestos manufacturers, however, Dow Corning maintains there is no link between implants and disease. The bankruptcy filing could give it time and negotiating leverage against plaintiffs' lawyers as it assembles scientific evidence to disprove their claims.

"We believe the science will continue to come in as it has been coming in, and that will ultimately assist in resolving this litigation," said John Churchfield, Dow Corning's chief financial officer.

Plaintiffs' lawyers responded angrily to the Chapter 11 filing. Rick Laminack, a Houston attorney whose firm represents more than 1,000 women who have opted out of the global settlement, said he will seek to separate claims against Dow Corning from those against Dow Chemical so his clients can continue to pursue their lawsuits against Dow Corning's parent.

"Dow Corning has filed bankruptcy in an effort to avoid trials and liability in breast implant lawsuits," Laminack said.

Richard A. Hazleton, chairman and chief executive, said Dow Corning "decided to take this action while we are in a position of financial strength, with the cash to continue operating our business without disruption.

"We are concerned about the settlement, since many are calling for hundreds of millions or even billions of more dollars and are predicting thousands of additional lawsuits," Hazleton added.

"We are continuing discussions with global settlement attorneys to reach a satisfactory agreement. But we have consistently said that we cannot both fund the global settlement and afford large numbers of lawsuits outside of the settlement."

Dow Corning had been telling attorneys in private negotiations for more than a year that it might be forced to file for Chapter 11 bankruptcy protection, although it only publicly acknowledged the possibility two weeks ago.

Dow Corning also has had trouble getting its insurers to fund the litigation battle. The company said it has obtained less than $100 million of the $1.5 billion it is seeking, and is suing some 100 carriers for more money.&lt;

Latest from the SFGATE homepage:

Click below for the top news from around the Bay Area and beyond. Sign up for our newsletters to be the first to learn about breaking news and more. Go to 'Sign In' and 'Manage Profile' at the top of the page.